Image display device and portable terminal device

ABSTRACT

An image display device includes a light source which emits laser light; an optical system which is operable to switch between a direct viewing mode of modulating the laser light and displaying the modulated light on a display section, and a projection mode of modulating the laser light and projecting the modulated light on a projection plane; and a control circuit which controls the optical system. The control circuit sets the optical system to the direct viewing mode at the time of activating an electric power source of the image display device.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a continuing application according to 37 C.F.R.1.53(b) and (j) of the International application number PCT/JP2008/58913filed on May 15, 2008, which in turn claims the benefit of Japanesepatent applications no. 2007-133443, filed on May 18, 2007 and2008-123545 filed on May 9, 2008, the disclosures of which applicationsare incorporated by reference herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to image display devices and portableterminal devices, and more particularly to an image display device and aportable terminal device having a mode of displaying an image on adisplay plane and a mode of projecting an image on a projection plane.

2. Disclosure of Related Art

A portable terminal device such as a portable phone is provided with adisplay section for displaying characters, images, and the like.Generally, the display section has a liquid crystal panel, and an imageis displayed on the display section by modulating light emitted from arear side of the liquid crystal panel by the liquid crystal panel inaccordance with an image signal. Specifically, light is modulated bycolor-separating the light from the rear side of the liquid crystalpanel by a color filter with respect to each pixel, and controllinglight transmission/blocking at each pixel position by a liquid crystalelement. The liquid crystal element has a transparent electrode withrespect to each pixel. Light transmission/blocking is controlled at eachpixel position by controlling a voltage to be applied to the transparentelectrodes.

In the portable terminal device having the above arrangement, anarrangement for displaying an image by a projector may be provided, inaddition to the arrangement for displaying an image by the liquidcrystal panel. For instance, a projector may be constituted of a laserlight source, and a light transmissive member attached with an opticalelement (such as a diffractive optical element or a holographic opticalelement). This arrangement contributes to miniaturization of aprojector.

However, miniaturization by the above arrangement has a limit. In thecase where a projector is loaded in a portable phone, for instance, thesize of the portable phone may be increased by a space corresponding tothe size of the projector.

In the case where the projector having the above arrangement is loadedin a portable phone or the like, light of a large amount is emitted tothe exterior of the projector when the projector is activated. In viewof this, it is necessary to securely avoid likelihood that light may beirradiated onto a human body, specifically, to the eyes of a human, whenthe projector is activated.

SUMMARY OF THE INVENTION

An image display device according to a first aspect of the presentinvention includes a light source; an optical system which is operableto switch between a direct viewing mode of modulating light from thelight source and displaying the modulated light on a display section,and a projection mode of modulating the light from the light source andprojecting the modulated light on a projection plane; and a controlcircuit which controls the optical system. The control circuit sets theoptical system to the direct viewing mode at the time of activating anelectric power source of the image display device.

A portable terminal device according to a second aspect of the presentinvention includes the image display device according to the firstaspect.

According to the present invention, a user is allowed to select betweentwo viewing modes i.e. the direct viewing mode of directly viewing thedisplay section and the projection mode of projecting the modulatedlight onto the projection plane. In this arrangement, the two viewingmodes are realized by distributing light to be emitted from the commonlight source by the optical system, and performing modulation dependingon the modes.

Further, since the optical system is always set to the direct viewingmode at the time of activating the electric power source, there is nolikelihood that light of a large amount may be erroneously emitted tothe exterior of the device.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects, and novel features of the present inventionwill become more apparent upon reading the following detaileddescription of the embodiment along with the accompanying drawings.

FIGS. 1A and 1B are diagrams showing an external appearance of aportable phone in Example 1 of the present invention.

FIG. 2 is a diagram showing an arrangement of the portable phone inExample 1.

FIGS. 3A and 3B are diagrams showing an arrangement of a PolymerDispersed Liquid Crystal in Example 1.

FIGS. 4A and 4B are diagrams for describing an operation of an opticalsystem in Example 1.

FIGS. 5A and 5B are diagrams for describing a modification of theoptical system in Example 1.

FIG. 6 is a diagram for describing a modification of the optical systemin Example 1.

FIGS. 7A and 7B are diagrams showing an arrangement of an optical systemin Example 2 of the present invention.

FIGS. 8A and 8B are diagrams showing an arrangement of a PolymerDispersed Liquid Crystal in Example 2.

FIG. 9 is a diagram showing an arrangement of a portable phone inExample 2.

FIGS. 10A, 10B, and 10C are diagrams showing a modification of theoptical system in Example 2.

FIGS. 11A and 11B are diagrams showing an arrangement of an opticalsystem in Example 3 of the present invention.

FIG. 12 is a diagram showing an arrangement of a portable phone inExample 3.

FIGS. 13A and 13B are flowcharts showing control processes to beperformed at the time of setting a projection mode in an embodiment ofthe present invention.

FIG. 14 is a flowchart showing a modification of the control process tobe performed at the time of setting a projection mode in the embodimentof the present invention.

FIG. 15 is a flowchart showing a modification of the control process tobe performed at the time of setting a projection mode in the embodimentof the present invention.

FIG. 16 is a flowchart showing a modification of the control process tobe performed at the time of setting a projection mode in the embodimentof the present invention.

FIG. 17 is a flowchart showing a process of setting a receiving mode inthe embodiment of the present invention.

FIGS. 18A and 18B are flowcharts showing control processes to beperformed during execution of the projection mode in the embodiment ofthe present invention.

FIGS. 19A and 19B are flowcharts showing a modification of the controlprocesses to be performed during execution of the projection mode in theembodiment of the present invention.

FIGS. 20A, 20B, and 20C are flowcharts showing control processes to beperformed at the time of activating the portable phone in the embodimentof the present invention.

FIGS. 21A and 21B are flowcharts showing processes of displaying abattery residual amount and a radio receiving state in the embodiment ofthe present invention.

FIGS. 22A and 22B are flowcharts showing processes of rendering aholographic image pattern in the embodiment of the present invention.

FIG. 23 is a diagram showing a state, in which the portable phone in theembodiment of the present invention is used in a TV conference system.

The drawings are provided mainly for describing the present invention,and do not limit the scope of the present invention.

DESCRIPTION OF PREFERRED EMBODIMENTS

In the following, an embodiment of the present invention is describedreferring to the drawings. The embodiment is directed to an arrangement,wherein the present invention is applied to a portable phone.

Example 1

FIGS. 1A and 1B are diagrams showing an external arrangement of aportable phone in Example 1. As shown in FIGS. 1A and 1B, the portablephone includes an upper casing 11, a lower casing 12, and a hingesection 13 for pivotally mounting the upper casing 11 on the lowercasing 12. The upper casing 11 has, on a front surface thereof, a maindisplay section 14, a sub camera 15, and a communications speaker 16;and the lower casing 12 has, on a front surface thereof, a key operatingsection 17 and a microphone 18. Further, the upper casing 11 has, on arear surface thereof, a sub display section 19, a main camera 20, and anexternal speaker 21; and the lower casing 12 has, on a rear surfacethereof, a battery storing section 22, an electric power supply terminal23, and a plug connecting section 24 to be connected with a power supplyplug.

FIG. 2 is a diagram showing an optical system and a circuitconfiguration of the portable phone. As shown in FIG. 2, the opticalsystem includes a laser light source 101, a mirror 102, diffractionlenses 103 and 104, a Polymer Dispersed Liquid Crystal (hereinafter,called as “PDLC”) 105, and a liquid crystal panel 106. Light transmittedthrough the liquid crystal panel 106 is emitted from the main displaysection 14 shown in FIG. 1.

The laser light source 101 is constructed by mounting three laserelements 101 a, 101 b, and 101 c respectively adapted to emit laserlight in a red wavelength band (hereinafter, called as “R light”), laserlight in a green wavelength band (hereinafter, called as “G light”), andlaser light in a blue wavelength band (hereinafter, called as “Blight”), on a substrate. The R light, the G light, and the B lightemitted from the laser elements 101 a, 101 b, and 101 c are reflected bythe mirror 102, and entered into the diffraction lens 103.

The diffraction lenses 103 and 104 are so configured as to exhibit afunction of a beam expander. The R light, the G light, and the B lightentered into the diffraction lens 103 are converted into parallel lightwhose beam diameters are expanded while being transmitted through thediffraction lenses 103 and 104, and then, entered into the PDLC 105.

FIGS. 3A and 3B are diagrams showing an arrangement of the PDLC 105. ThePDLC 105 is constructed by encapsulating capsules 105 b, each of whichis encapsulated with liquid crystal molecules, and a special polymer 105a between transparent electrodes 105 c and 105 d disposed opposite toeach other. The liquid crystal molecules encapsulated in the capsules105 b are randomly oriented in a state that a voltage is not appliedbetween the transparent electrodes 105 c and 105 d (see FIG. 3A). Inthis state, light entered into the PDLC 105 is scattered by the liquidcrystal molecules. Light scattering by the PDLC 105 reduces thecoherence of R light, G light, and B light emitted from the laser lightsource 101.

On the other hand, when a voltage is applied between the transparentelectrodes 105 c and 105 d, as shown in FIG. 3B, the orientations of theliquid crystal molecules are aligned, and accordingly, light enteredinto the PDLC 105 propagates without being scattered by the liquidcrystal molecules. Light transmitted through the PDLC 105 without beingscattered by the PDLC 105 can be guided to the liquid crystal panel 106in a state that the coherence of R light, G light, and B light emittedfrom the laser light source 101 is maintained. In this condition, it isdesirable to guide, to the liquid crystal panel 106, light having such acoherence as to generate an image by diffraction, using a hologrampattern to be described later.

Application/non-application of a voltage to the transparent electrodes105 c and 105 d is controlled by a liquid crystal driver 202 shown inFIG. 2.

Referring back to FIG. 2, the liquid crystal panel 106 has a colorfilter for color-separating incident light with respect to each pixel, aliquid crystal into which light subjected to color separation isentered, and transparent electrodes for applying a voltage to the liquidcrystal at each pixel position. The liquid crystal panel 106 imparts amodulation function or a diffraction function to laser light transmittedthrough the PDLC 105 in accordance with a drive control from a paneldriver 203.

When the PDLC 105 is in a state shown in FIG. 3A, similarly to imagedisplay to be performed by an existing portable phone, an image patternfor generating an image by light transmission/blocking at each pixelposition (hereinafter, called as a “normal image pattern”) is renderedon the liquid crystal panel 106. On the other hand, in the case wherethe PDLC 105 is in a state shown in FIG. 3B, a hologram pattern forgenerating an image by diffracting entered laser light (hereinafter,called as a “holographic image pattern”) is rendered on the liquidcrystal panel 106. An image is displayed by projecting the laser lightdiffracted by the holographic image pattern onto a desk surface, a wallsurface, or a like surface.

It is desirable to set the resolution of the liquid crystal panel 106 tosuch a value that a hologram is renderable with a smaller pitch(preferably, a pitch in the micron order). For instance, a hologram isrenderable with a pitch in the micron order by using an existing microdisplay panel as the liquid crystal panel 106.

The circuit system of the portable phone includes a laser driver 201,the liquid crystal driver 202, the panel driver 203, an image processingunit 204, a key unit 205, a camera unit 206, a microphone/speaker unit207, a communications processing unit 208, an electric power source unit209, a sensor unit 210, and a controller 211.

The laser driver 201 drives the laser light source 101 in accordancewith a control from the controller 211.

The liquid crystal driver 202 drives the PDLC 105 in accordance with acontrol from the controller 211. Specifically, when the portable phoneis in a state that an image is displayed, with the user being allowed todirectly view the main display section 14 (hereinafter, called as“direct viewing mode”), a voltage is not applied between the transparentelectrodes 105 c and 105 d (see FIG. 3A); and when the portable phone isin a state that an image is displayed with laser light being projectedonto a desk surface, a wall surface, or the like (hereinafter, called as“projection mode”), a predetermined voltage is applied between thetransparent electrodes 105 c and 105 d (see FIG. 3B).

The panel driver 203 renders a predetermined pattern on the liquidcrystal panel 106 in accordance with a drive signal from the imageprocessing unit 204. Specifically, when the portable phone is in thedirect viewing mode, a normal image pattern in accordance with an imagesignal is rendered on the liquid crystal panel 106, and when theportable phone in the projection mode, a holographic image pattern inaccordance with an image signal is rendered on the liquid crystal panel106.

The image processing unit 204 processes e.g. an image signal inputtedfrom an external device, characters/image data (e.g. data received by anelectronic mail) to be inputted through the communications processingunit 208, image data to be inputted through the camera unit 206, andcharacter data to be inputted through the key unit 205, generates adrive signal corresponding to a pattern to be rendered on the liquidcrystal panel 106, and supplies the generated drive signal to the paneldriver 203.

In this example, upon receiving a command signal indicating whether thedisplay mode is the direct viewing mode or the projection mode, theimage processing unit 204 generates a drive signal in accordance withthe command signal, and supplies the drive signal to the panel driver203. Specifically, when the portable phone is in the direct viewingmode, a drive signal corresponding to a normal image pattern is suppliedto the panel driver 203, and when the portable phone is in theprojection mode, a drive signal corresponding to a holographic imagepattern is supplied to the panel driver 203.

The image processing unit 204 supplies, to the panel driver 203, a drivesignal for displaying a radio receiving state, a battery residualamount, and a predetermined formatted screen in accordance with acommand from the controller 211.

The image processing unit 204 further includes a routine for processingpicked up image information to be supplied from the camera 206 for facerecognition. In the case where a face image is detected in a picked-upimage, a signal indicating the detection is supplied to the controller211.

The key unit 205 has the key operating section 17 shown in FIG. 1A, andsupplies a signal in accordance with a key operation to the controller211 and the image processing unit 204. The camera unit 206 has the subcamera 15 and the main camera 20 shown in FIGS. 1A and 1B, and outputssignals indicating images picked up by the sub camera 15 and the maincamera 20 to the image processing unit 204.

The microphone/speaker unit 207 has the microphone 18, thecommunications speaker 16, and the external speaker 21 shown in FIGS. 1Aand 1B. The microphone/speaker unit 207 synthesizes an audio signalinputted through the microphone 18 during a phone call with an audiosignal from a recipient of the phone call, outputs the synthesis resultthrough the communications speaker 16; and transmits the synthesisresult to the telephone of the recipient through the communicationsprocessing unit 208. Further, the microphone/speaker unit 207 outputs apredetermined formatted voice message through the communications speaker16 and the external speaker 21 in accordance with a command from thecontroller 211.

The communications processing unit 208 has an antenna and acommunications processing circuit, and performs a communications processwith other terminal devices.

The electric power source unit 209 has the battery storing section 22,the electric power supply terminal 23, and the plug connecting section24 shown in FIG. 1B, and supplies an electric power source to therespective parts. Further, the electric power source unit 209 suppliesthe controller 211 with a signal indicating whether a commercialelectric power source is supplied.

The sensor unit 210 includes an acceleration sensor for detecting anacceleration of a portable phone main body, a tilt sensor for detectinga tilt state of the portable phone main body with respect to ahorizontal state, and a hinge sensor for detecting a tilt angle (foldingangle) of the upper casing 11 with respect to the lower casing 12. Thesensor unit 210 supplies detection results by the sensors to thecontroller 211.

Next, an image display operation is described referring to FIGS. 4A and4B.

When the portable phone is in the direct viewing mode shown in FIG. 4A,a voltage is not applied from the liquid crystal driver 202 to the PDLC105, and a normal image pattern is rendered on the liquid crystal panel106. R light, G light, and B light outputted from the laser light source101 are reflected by the mirror 102, and the beam diameters thereof areexpanded by the diffraction lenses 103 and 104. In this arrangement,since the PDLC 105 is in the state shown in FIG. 3A, the R light, the Glight, and the B light are diffused on the PDLC 105, and entered intothe liquid crystal panel 106. Then, the incident light is modulatedaccording to the normal image pattern rendered on the liquid crystalpanel 106 with respect to each pixel, and outputted from the maindisplay section 14 shown in FIG. 1. The user is then allowed to see adisplay image by directly viewing the main display section 14.

When the portable phone is in the projection mode shown in FIG. 4B, avoltage is applied from the liquid crystal driver 202 to the PDLC 105,and a holographic image pattern is rendered on the liquid crystal panel106. R light, G light, and B light outputted from the laser light source101 are reflected by the mirror 102, and the beam diameters thereof areexpanded by the diffraction lenses 103 and 104. In this arrangement,since the PDLC 105 is in the state shown in FIG. 3B, the R light, the Glight, and the B light propagate without being diffused on the PDLC 105,and are entered into the liquid crystal panel 106. Then, the incidentlight is diffracted according to the holographic image pattern renderedon the liquid crystal panel 106, and outputted from the main displaysection 14 shown in FIG. 1A. The user is then allowed to see a displayimage by projecting the laser light to be emitted from the main displaysection 14 onto a desk surface, a wall surface, or the like.

As described above, in this example, the user is allowed to select, asnecessary, one of two display modes i.e. the direct viewing mode ofdirectly viewing the main display section 14, and the projection mode ofprojecting laser light onto a desk surface, a wall surface, or the like.

In this example, all the elements of the optical system from the laserlight source 101 to the liquid crystal panel 106 are used in commonbetween the two display modes. In this arrangement, there is nolikelihood that the arrangement of the optical system may be complicateddue to addition of a projection mode, and the size of the optical systemmay be increased. Thus, the example is advantageous in adding aprojector function, while suppressing an increase in the size of theportable phone main body.

In this example, the beam diameter is expanded by the two diffractionlenses 103 and 104. Alternatively, the beam diameter may be expanded byusing a beam expander constituted of combination of a concave lens and aconvex lens. The modification, however, increases the size of a beamexpander, as compared with the case in example, with the result that thesize of the portable phone main body may be increased.

Further alternatively, an arrangement shown in FIGS. 5A and 5B may beemployed as means for increasing a laser light incident area withrespect to the liquid crystal panel 106, in place of a beam expander.Referring to FIGS. 5A and 5B, the reference numeral 111 indicates amirror for reflecting one-third of R light, G light, and B light to beemitted from the laser light source 101, and transmitting two-thirdsthereof, 112 indicates a mirror for reflecting one-half of R light, Glight, and B light transmitted through the mirror 111, and transmittingone-half thereof, and 113 indicates a mirror for reflecting all of Rlight, G light, and B light transmitted through the mirror 112.

In the above modification example, the light amounts of R light, Glight, and B light that have been reflected by the mirrors 111, 112, and113 are made substantially equal to each other. In this arrangement, thelaser light entered area with respect to the liquid crystal panel 106 isincreased in X-axis direction in FIGS. 5A and 5B. In order to increase alaser light entered area in Z-axis direction in FIGS. 5A and 5B as wellas X-axis direction, for instance, as shown in FIG. 6, mirror groups(mirror groups 1, 2, and 3) each constituted of mirrors 111, 112, and113 may be aligned in three rows in Z-axis direction, and mirrors 121,122, and 123 for equally distributing light from the laser light source101 with respect to the mirror groups may be disposed.

In the configuration examples shown in FIGS. 4A and 4B, and FIGS. 5A and5B, optical axes of R light, G light, and B light are displaced fromeach other depending on a difference in position between laser elements101 a, 101 b, and 101 c. In the case where the optical axis displacementaffects a display image, an element for aligning the optical axes of Rlight, G light, and B light, such as a diffraction element, may bedisposed right behind the laser light source 101.

Example 2

In Example 1, laser light is allowed to be entered into the PDLC 105from the rear side of the liquid crystal panel. In this example, laserlight is allowed to be entered into a PDLC from a lateral side of aliquid crystal panel. In Example 1, the liquid crystal panel 106 is usedin common as an imager between the direct viewing mode and theprojection mode. In this example, an imager for the direct viewing mode,and an imager for the projection mode are individually provided.

FIGS. 7A and 7B are diagrams showing an optical system in this example.As shown in FIGS. 7A and 7B, in this example, alight source unit 131, adichroic prism array 132, a PDLC 133, and a liquid crystal panel 134 areprovided, in addition to the liquid crystal panel 106.

The light source unit 131 has three laser light sources 131 a, 131 b,and 131 c for emitting R light, G light, and B light, respectively. TheR light, the G light, and the B light are emitted from the laser lightsources 131 a, 131 b, and 131 c in Y-axis direction. The R light emittedfrom the laser light source 131 a is reflected in X-axis direction by amirror surface 132 a of the dichroic prism array 132, and transmittedthrough mirror surfaces 132 b and 132 c. The G light emitted from thelaser light source 131 b is reflected in X-axis direction by the mirrorsurface 132 b of the dichroic prism array 132, and transmitted throughthe mirror surface 132 c. The B light emitted from the laser lightsource 131 c is reflected in X-axis direction by the mirror surface 132c of the dichroic prism array 132. In this way, the optical axes of Rlight, G light, and B light are aligned to each other, and entered intothe PDLC 133 in X-axis direction.

FIG. 8A shows an arrangement of the PDLC 133. Similarly to the PDLC 105in Example 1, the PDLC 133 is constructed by encapsulating capsules,each of which is encapsulated with liquid crystal molecules, and aspecial polymer. In this example, however, transparent electrodes 133 bare arranged spaced apart from each other with a predetermined intervalin X-axis direction. When a switch 202 b shown in FIG. 8A is turned on,the plus potential and the minus potential of an electric power source202 a are respectively applied to the each adjacent two transparentelectrodes 133 b. Accordingly, an electric potential is applied to aportion partitioned by the transparent electrodes 133 b.

Similarly to Example 1, the liquid crystal molecules encapsulated in thecapsules are randomly oriented in a state that a voltage is not appliedbetween the transparent electrodes 133 b. Accordingly, light enteredinto the PDLC 133 is scattered by the liquid crystal molecules. On theother hand, when a voltage is applied between the transparent electrodes133 b, the orientations of the liquid crystal molecules are aligned inX-axis direction. Accordingly, incident light into the PDLC 133propagates without being scattered by the liquid crystal molecules.

Similarly to Example 1, FIG. 8A shows the PDLC 133 having a propertythat the orientations of liquid crystal molecules are aligned in avoltage applying direction. Alternatively, for instance, in the casewhere the orientations of liquid crystal molecules are aligned in adirection perpendicular to the voltage applying direction, as shown inFIG. 8B, transparent electrodes 133 c and 133 d may be disposed at sucha position as to interpose a layer of liquid crystal molecules 133 etherebetween in Y-axis direction.

In the direct viewing mode shown in FIG. 7A, a voltage is not applied tothe PDLC 133. In this case, since the orientations of liquid crystalmolecules are random, R light, G light, and B light entered into thePDLC 133 are scattered by the liquid crystal molecules. A part of thescattered R light, G light, and B light is irradiated toward the liquidcrystal panel 106 through an upper surface of the PDLC 133; and a partthereof is reflected by a mirror surface 133 a formed on a lower surfaceof the PDLC 133, and then irradiated toward the liquid crystal panel 106through the upper surface of the PDLC 133. Thus, similarly to Example 1,in the direct viewing mode shown in FIG. 7A, R light, G light, and Blight emitted from the light source unit 131 are guided to the liquidcrystal panel 106 as backlight.

In the projection mode shown in FIG. 7B, a voltage is applied to thePDLC 133. In this case, since the orientations of liquid crystalmolecules are aligned in X-axis direction, R light, G light, and B lightentered into the PDLC 133 propagate and transmit through the liquidcrystal panel 134 without being scattered by the liquid crystalmolecules. The transmitted R light, G light, and B light are enteredinto the liquid crystal panel 134 disposed at the exit side of the PDLC133. The resolution of the liquid crystal panel 134 is set to such avalue that a hologram is renderable with a pitch in the micron order.For instance, an existing micro display panel is used as the liquidcrystal panel 134.

A hologram pattern (a holographic image pattern) for generating an imageby diffracting entered R light, G light, and B light is rendered on theliquid crystal panel 134. An image is displayed by projecting R light, Glight, and B light subjected to diffraction according to a holographicimage pattern onto a projection plane (such as a desk surface or a wallsurface). A projection opening through which R light, G light, and Blight are projected is formed in a top portion of an upper casing 11 ofa portable phone. An image is projected onto the projection plane byplacing the portable phone on a desk or the like in a state that theback surface of a lower casing 12 is contacted with the desk surface orthe like, and pivotally rotating the upper casing 11 to such a positionas to direct the projection opening toward the projection plane.

FIG. 9 is a diagram showing a circuit configuration for driving andcontrolling the optical system in this example. Elements having the samearrangement as those described in Example 1 referring to FIG. 2 areindicated with the same reference numerals, and description thereof isomitted herein.

In FIG. 9, similarly to Example 1, a laser driver 201 drives a laserlight source 101 in accordance with a control from a controller 211. Aliquid crystal driver 202 drives the PDLC 133 in accordance with acontrol from the controller 211. Specifically, when the portable phoneis in the direct viewing mode, a voltage is not applied between thetransparent electrodes 133 b, and when the portable phone is in theprojection mode, a predetermined voltage is applied between thetransparent electrodes 133 b.

A panel driver 220 renders a predetermined pattern on the liquid crystalpanel 106 and the liquid crystal panel 134 in accordance with a drivesignal from an image processing unit 204. Specifically, when theportable phone is in the direct viewing mode, a normal image pattern inaccordance with an image signal is rendered on the liquid crystal panel106, and when the portable phone is in the projection mode, aholographic image pattern in accordance with an image signal is renderedon the liquid crystal panel 134.

In this example, the user is allowed to select, as necessary, one of twodisplay modes i.e. the direct viewing mode of directly viewing a maindisplay section 14, and the projection mode of projecting laser lightonto a desk surface, a wall surface, or the like. In this example, theoptical system from the light source unit 131 to the liquid crystalpanel 133 is used in common between the two display modes. This enablesto simplify the arrangement of the optical system, and miniaturize theoptical system. Thus, the example is advantageous in adding a projectorfunction, while suppressing an increase in the size of the portablephone main body.

Further, in this example, since a liquid crystal panel havingsubstantially the same resolution as the resolution of an existingportable phone is usable as the liquid crystal panel 106, cost reductioncan be achieved, as compared with the case in Example 1. In other words,in Example 1, a high resolution liquid crystal panel is used as theliquid crystal panel 106 to render a holographic image pattern. Sincethe liquid crystal panel 106 has a large display area, use of the highresolution liquid crystal panel as the liquid crystal panel 106 mayincrease the cost. On the other hand, in this example, since a liquidcrystal panel having substantially the same resolution as the resolutionof an existing portable phone is usable as the liquid crystal panel 106,as compared with Example 1, the cost can be considerably reduced. Sincethe display area of the liquid crystal panel 134 for use in rendering aholographic image pattern is small, use of a high resolution liquidcrystal panel as the liquid crystal panel 134 does not considerablyincrease the cost. In view of the above, as compared with Example 1,this example is advantageous in reducing the cost.

In this example, as shown in FIG. 10A, laser light is allowed to bedirectly entered into the PDLC 133 from the dichroic prism 132. FIG. 10Ais a diagram of the optical system viewed from above.

In this arrangement, in the case where laser light is not expandedwithin the PDLC 133 in such a manner as to cover the display area of theliquid crystal panel 106, for instance, as shown in FIG. 10B, anarrangement for inserting or retracting a lens 135 for expanding laserlight in X-Z plane direction on or from the optical path of laser lightmay be provided. In the modification, when the portable phone is in thedirect viewing mode, the lens 135 is inserted on the optical path oflaser light, whereby the laser light is expanded in X-Z plane direction.When the portable phone is in the projection mode, the lens is retractedfrom the optical path of laser light, whereby the laser light is enteredinto the PDLC 133 without being expanded in X-Z plane direction. In thismodification, the initial position of the lens 135 is set to such aposition that the lens 135 is inserted on the optical path of laserlight. In the modification, since the lens 135 is inserted on theoptical path of laser light when the electric power source of theportable phone is activated, it is less likely that laser light having ahigh coherence may reach the liquid crystal panel 134 for diffraction,thereby enhancing safe use of the portable phone.

Alternatively, an active lens element of exhibiting a lens function inaccordance with a drive signal, such as a liquid crystal lens, may beused in place of the lens 135. FIG. 10C is a diagram showing theconfiguration example of the modification. In this example, an activelens element 136 is disposed in place of the lens 135. The active lenselement 136 is controlled to be turned on and off in accordance with adrive signal to control the propagating direction of laser light. Whenthe portable phone is in the direct viewing mode, laser light isexpanded in X-Z plane direction by the active lens element 136. When theportable phone is in the projection mode, laser light propagates throughthe active lens element 136 without being expanded in X-Z planedirection, and is entered into the PDLC 133. In the modification, theactive lens element 136 is so configured as to exhibit a lens functionin an off-state (a state that a drive signal is not applied). Thus,laser light is expanded e.g. when the electric power source isactivated. Accordingly, it is less likely that laser light having a highcoherence may reach the liquid crystal panel 134 for diffraction,thereby enhancing safe use of the portable phone.

Example 3

In Example 2, the PDLC 133 is operable to switch between the directviewing mode and the projection mode. In this example, the directviewing mode and the projection mode are switched by combination of apolarized light rotator and a polarized beam splitter.

FIGS. 11A and 11B show an optical system in Example 3. Elements inExample 3 substantially identical or equivalent to those in Examples 1and 2 are indicated with the same reference numerals, and descriptionthereof is omitted herein.

In this example, similarly to Example 2, a light source unit 131 and adichroic prism 132 are provided for irradiating R light, G light, and Blight. Further, similarly to Example 1, diffraction lenses 103 and 104are provided for expanding the beam diameters of R light, G light, and Blight. Furthermore, a liquid crystal panel 134 is provided for renderinga holographic image pattern in the projection mode. A diffuser 142 isalso provided for diffusing R light, G light, and B light transmittedthrough the diffraction lens 104.

In addition to the above, in this example, a polarized light rotator 140and a polarized beam splitter 141 are provided. The polarized lightrotator 140 changes polarization directions of R light, G light, and Blight in accordance with a drive signal. An example of the polarizedlight rotator 140 is a liquid crystal panel such as a TN liquid crystal.

When the portable phone is in the direct viewing mode as shown in FIG.11A, the polarized light rotator 140 is kept in an off-state (a statethat a drive signal is not applied). In this state, R light, G light,and B light are entered into the polarized beam splitter 141 asS-polarized light, and reflected by the polarized beam splitter 141.Thereafter, the R light, the G light, and the B light have the beamdiameters thereof expanded by the diffraction lenses 103 and 104, andthen diffused on the diffuser 142. Thus, when the portable phone is inthe direct viewing mode, similarly to Example 1, R light, G light, and Blight emitted from the light source unit 131 are guided to a liquidcrystal panel 106 as backlight.

When the portable phone is in the projection mode as shown in FIG. 11B,the polarized light rotator 140 is kept in an on-state (a state that adrive signal is applied). In this state, R light, G, light and B lightare entered into the polarized beam splitter 141 as P-polarized light,and transmitted through the polarized beam splitter 141. The transmittedR light, G light, and B light are entered into the liquid crystal panel134. Similarly to Example 2, the resolution of the liquid crystal panel134 is set to such a value that a hologram is renderable with a pitch inthe micron order. For instance, an existing micro display device is usedas the liquid crystal panel 134.

A hologram pattern (a holographic image pattern) for generating an imageby diffracting the entered R light, G light, and B light is rendered onthe liquid crystal panel 134. An image is displayed by projecting Rlight, G light, and B light subjected to diffraction according to aholographic image pattern onto a projection plane (such as a desksurface or a wall surface). Similarly to Example 2, a projection openingthrough which R light, G light, and B light are projected is formed in atop portion of an upper casing 11 of the portable phone. Placing theportable phone on a desk or the like, and pivotally rotating the uppercasing 11 to such a position as to direct the projection opening towardthe projection plane enables to project an image onto the projectionplane.

FIG. 12 is a diagram showing a circuit configuration for driving andcontrolling the optical system in this example. Elements having the samearrangement as those described in Examples 1 and 2 referring to FIGS. 2and 9 are indicated with the same reference numerals, and descriptionthereof is omitted herein.

In FIG. 12, a polarized light driver 221 drives the polarized lightrotator 140 in accordance with a control from a controller 211.Specifically, the polarized light driver 221 sets the polarized lightrotator 140 to an off-state (a state that a drive signal is not applied)when the portable phone is in the direct viewing mode, and sets thepolarized light rotator 140 to an on-state (a state that a drive signalis applied) when the portable phone is in the projection mode.

Similarly to Example 2, a panel driver 220 renders a normal imagepattern in accordance with an image signal on the liquid crystal panel106 when the portable phone is in the direct viewing mode, and renders aholographic image pattern in accordance with an image signal on theliquid crystal panel 134 when the portable phone is in the projectionmode.

Similarly to Examples 1 and 2, in this example, the user is allowed toselect, as necessary, one of two display modes i.e. the direct viewingmode of directly viewing a main display section 14, and the projectionmode of projecting laser light onto a desk surface, a wall surface, orthe like. In this example, the optical system from the light source unit131 to the polarized beam splitter 141 is used in common between the twodisplay modes. This enables to simplify the arrangement of the opticalsystem and miniaturize the optical system. Thus, the example isadvantageous in adding a projector function, while suppressing anincrease in the size of the portable phone main body. Further, in thisexample, since a liquid crystal panel having substantially the sameresolution as the resolution of an existing portable phone is usable asthe liquid crystal panel 106, similarly to Example 2, the cost can bereduced.

In this example, the polarized beam splitter 141 is used as means forchanging the optical paths of R light, G light, and B light.Alternatively, a wire grid polarized light separating element may beused, in place of the polarized beam splitter 141. Use of the wire gridpolarized light separating element is advantageous in reducing theweight of a portable phone.

In the case where the polarized beam splitter 141 is used, it isnecessary to switch the polarization directions of R light, G light, andB light between Y-axis direction (P-polarization direction) and Z-axisdirection (S-polarization direction) shown in FIG. 12. However, if awire grid polarized light separating element is used, sincetransmission/reflection is determined based on a relation between thedirection of grid pitch and the polarization directions of R light, Glight, and B light, the polarization directions of R light, G light, andB light are not necessarily aligned with Y-axis direction(P-polarization direction) or Z-axis direction (S-polarizationdirection), and may be aligned with a polarization direction other thanthe above. Accordingly, use of a wire grid polarized light separatingelement is advantageous in increasing the latitude in the position oflaser light sources 131 a, 131 b, and 131 c, thereby increasing thedesign latitude of an optical system.

In this example, R light, G light, and B light are allowed to be enteredinto the polarized beam splitter 141 in X-axis direction. Alternatively,it is possible to allow R light, G light, and B light to be entered intothe polarized beam splitter 141 in Y-axis direction. In themodification, the laser light sources 131 a through 131 c are disposedat such positions that R light, G light, and B light are entered intothe polarized beam splitter 141 as P-polarized light when the polarizedlight rotator 140 is in an off-state. Since the polarized light rotator140 is kept in an off-state when the portable phone is in a normaloperation state e.g. at the time of activating the electric power sourceof the portable phone, there is no likelihood that laser light is guidedto the liquid crystal panel 134 by reflection on the polarized beamsplitter 141.

Control Process by Portable Phone

In Example 1, in the case where the projection mode is selected, laserlight having a high coherence is emitted from the main display section14 to be directly viewed when the portable phone is in a normal usestate. Likewise, in Examples 2 and 3, laser light having a highcoherence is emitted through the projection opening formed in the topportion of the upper casing 11. In view of this, it is necessary tosecurely avoid likelihood that laser light may be irradiated onto ahuman body, in the case where the projection mode is set as a displaymode.

In the following, control processes for avoiding a likelihood that laserlight may be irradiated onto a human body are described process byprocess, referring to FIGS. 13A and 13B through FIGS. 19A and 19B. Itshould be noted that the direct viewing mode is always set as thedisplay mode at the time of activating the portable phone.

FIG. 13A is a process to be performed when the projection mode isselected. Upon manipulation of the key operating section 17 and input ofa command indicating selecting the projection mode (Step S101), abuild-in timer is activated (Step S102), and judgment is made whether apassword has been inputted (Step S103). If it is judged that a passwordhas not been inputted within a predetermined time T0 (YES in Step S104),the user is notified that the portable phone is not allowed to switch tothe projection mode, and then, a projection mode setting method isnotified (Step S105). Specifically, the user is requested to input apassword. The notification is executed by display on the main displaysection 14 and/or audio output through the external speaker 21.

If the password has not been correctly inputted upon lapse of apredetermined time after the notification, the projection mode settingis suspended.

In the case where the password has been correctly inputted within thetime T0, or the password has been correctly inputted after thenotification in Step S105 (YES in Step S103), the user is notified thatthe portable phone is switched to the projection mode (Step S106).Thereafter, the projection mode is started (Step S107). The projectionmode may be started upon input of confirmation operation after thenotification in Step S106 in order to obtain higher security.

In FIG. 13B, the display mode is locked to the direct viewing mode, andthe portable phone is not allowed to switch to the projection modeunless the portable phone is released from the locked state. In thecontrol flow shown in FIG. 13B, Step S110 is provided in place of StepS103 in the control flow shown in FIG. 13A. Specifically, judgment ismade as to whether a process of releasing the portable phone from thedirect viewing mode has been properly performed, in place of judgment asto whether a password has been inputted correctly, and the process afterS106 is executed, if it is judged that the process of releasing thelocked state has been properly performed.

In the control processes shown in FIGS. 13A and 13B, input of a passwordor releasing a locked state is requested to set the projection mode, inaddition to an operation input for setting the projection mode. Thisenables to avoid likelihood that a child or an unauthenticated personmay select the projection mode. Further, since a complex procedure isnecessary to switch the portable phone to the projection mode, easyselection of the projection mode is avoided.

In the control process shown in FIG. 14, judgment is made whether an ACelectric power source (a commercial electric power source) has beenconnected to the portable phone, in addition to the judgment processshown in FIG. 13A, and the projection mode is set if it is judged thatthe AC electric power source has been connected. In FIG. 14, processsteps S120 through S122 are added to the process flow shown in FIG. 13A.Specifically, even if it is judged that the password has been properlyinputted in Step S103, it is judged whether an AC electric power sourcehas been connected to the portable phone in Step S120.

Judgment as to whether an AC electric power source has been connected tothe portable phone is made by judging whether a signal indicatingconnection to an AC electric power source has been inputted from theelectric power source unit 209 to the controller 211 shown in FIGS. 2,9, and 12.

If connection to an AC electric power source has not been detectedwithin the predetermined time T0 (YES in Step S121), the user isnotified that the portable phone is not allowed to switch to theprojection mode, and then, is requested to connect to an AC electricpower source (Step S122). The notification is executed by display on themain display section 14 and/or audio output through the external speaker21.

If connection to an AC electric power source has not been detected uponlapse of a predetermined time after the notification, the projectionmode setting is suspended.

In the case where connection to an AC electric power source has beendetected within the time T0, or connection to an AC electric powersource has been detected after the notification in Step S122 (YES inStep S120), the user is notified that the portable phone is switched tothe projection mode (Step S106). Thereafter, the projection mode isstarted (Step S107).

Generally, in the case where an image is displayed in the projectionmode, it is necessary to set the output of the laser light source 101higher than the output in the direct viewing mode. As a result, theelectric power consumption in the projection mode is increased, ascompared with the electric power consumption in the direct viewing mode.Accordingly, it is preferable to use the portable phone in theprojection mode by connecting the portable phone to an AC electric powersource. In view of this, requesting connection to an AC electric powersource, as shown in the control process of FIG. 14, is advantageous insecurely avoiding wear of a battery, and allowing the user to recognizethat the portable phone is switched to the projection mode.

In the control process shown in FIG. 15, judgment is made as to whetherthe portable phone is placed on a desk or the like, in addition to thejudgment process shown in FIG. 13A, and the projection mode is set if itis judged that the portable phone is in a placement state. In FIG. 15,process steps S130 through S132 are added to the process flow shown inFIG. 13A. Specifically, even if it is judged that the password has beenproperly inputted in Step S103, it is judged whether the portable phoneis in a placement state in Step S130.

Judgment as to whether the portable phone is in a placement state ismade based on a detection signal from the acceleration sensor to beinputted from the sensor unit 210 to the controller 211 shown in FIGS.2, 9, and 12. In other words, if the acceleration is zero, it is judgedthat the portable phone is in a placement state.

If it is judged that the portable phone is not in a placement statewithin the predetermined time T0 (YES in Step S131), the user isnotified that the portable phone is not allowed to switch to theprojection mode, and then, is requested to place the portable phone(Step S132). The notification is executed by display on the main displaysection 14 and/or audio output through the external speaker 21.

If it is judged that the portable phone is not placed upon lapse of apredetermined time after the notification, the projection mode settingis suspended.

In the case where it is judged that the portable phone is placed withinthe time T0, or the portable phone is placed after the notification inStep S132 (YES in Step S130), similarly to the above, the user isnotified that the portable phone is switched to the projection mode(Step S106). Thereafter, the projection mode is started (Step S107).

Generally, in the case where an image is displayed in the projectionmode, the portable phone is supposed to be used, while being placed on adesk or the like. If the portable phone is switched to the projectionmode, while the user holds the portable phone, laser light could beerroneously irradiated onto a person. In view of this, judging whetherthe portable phone has been placed, as shown in the control process ofFIG. 15, is advantageous in securely avoiding erroneous irradiation oflaser light onto a person, and allowing the user to recognize that theportable phone is switched to the projection mode.

In the control process shown in FIG. 16, judgment is made as to whetherthe folding angle (the pivot angle of the upper casing 11 with respectto the lower casing 12) of the portable phone is properly set, inaddition to the judgment process in FIG. 13A, and the projection mode isset if it is judged that the folding angle is properly set. In FIG. 16,process steps S140 through S142 are added to the process flow shown inFIG. 13A. Specifically, even if it is judged that the password has beenproperly inputted in Step S103, it is judged whether the folding angleof the portable phone is properly set in Step S140.

Judgment as to whether the folding angle is properly set is made basedon a detection signal from the hinge sensor to be inputted from thesensor unit 210 to the controller 211 shown in FIGS. 2, 9, and 12.

If it is judged that the folding angle of the portable phone is notproperly set within the predetermined time T0 (YES in Step S141), theuser is notified that the portable phone is not allowed to switch to theprojection mode, and then, is requested to adjust the folding angle ofthe portable phone (Step S142). The notification is executed by displayon the main display section 14 and/or audio output through the externalspeaker 21.

If it is judged that the folding angle is not properly set upon lapse ofa predetermined time after the notification, the projection mode settingis suspended.

In the case where it is judged that the folding angle is properly setwithin the time T0, or the folding angle is properly set after thenotification in Step S142 (YES in Step S140), similarly to the above,the user is notified that the portable phone is switched to theprojection mode (Step S106). Thereafter, the projection mode is started(Step S107).

Generally, in the case where an image is displayed in the projectionmode, the portable phone is placed on a desk or the like, and is used,with the folding angle thereof being adjusted in a predetermined range.In the arrangement of Example 1, if the portable phone is switched tothe projection mode in a state that the upper casing 11 of the portablephone is fully opened or nearly fully opened, a laser light irradiationdirection is directed upwardly, resulting in that laser light could beerroneously irradiated onto a person. Further, in the arrangement ofExample 1, if the upper casing 11 of the portable phone is opened withan undesirable angle, laser light could be erroneously irradiated onto aperson. In view of this, additionally judging whether the folding angleof the portable phone is properly set, as shown in the control processof FIG. 16, is advantageous in securely avoiding erroneous irradiationof laser light onto a person, and allowing the user to recognize thatthe portable phone is switched to the projection mode.

FIG. 17 is a flowchart showing a process flow to be performed inselecting and setting a notification to a user that the portable phonehas received a phone call or an electronic mail from another terminaldevice during execution of the projection mode.

If a ring tone for notifying receiving of a phone call or an electronicmail is outputted during execution of the projection mode, a person mayinadvertently pick up the portable phone or approach the portable phone,resulting in that laser light could be erroneously irradiated onto theperson. In order to avoid the likelihood, it is desirable to turn off aring tone, or superimposedly display a message notifying that theportable phone has received a phone call or an electronic mail on aprojection screen during execution of the projection mode.

In the process flow shown in FIG. 17, if it is judged that a passwordhas been properly inputted in Step S103 shown in FIG. 13A, the routineproceeds to a process of selecting a receiving mode during execution ofthe projection mode (Step S151). In this embodiment, three notificationmodes i.e. an audio notification mode (Step S152), a screen notificationmode (Step S153), and a notification inhibiting mode (Step S154) arepresented to the user as options.

The audio notification mode is a mode of notifying receiving a phonecall or an electronic mail by way of a ring tone. The screennotification mode is a mode of notifying receiving a phone call or anelectronic mail by superimposedly displaying characters or the likeindicating the receiving on a display screen. In the screen notificationmode, notification of receiving by way of audio sounds is not performed.The notification inhibiting mode is a mode of inhibiting notification ofreceiving a phone call and an electronic mail.

If an intended mode is selected from among the three receiving modes,receiving notification is performed in accordance with the selected modeduring execution of the projection mode. Thereafter, similarly to theabove, the user is notified that the portable phone is switched to theprojection mode (Step S106). Thereafter, the projection mode is started(Step S107).

Next, a control process for preventing erroneous irradiation of laserlight in advance, in view of likelihood that laser light could bedirected to a person during execution of the projection mode, isdescribed referring to FIGS. 18A, 18B, 19A, and 19B.

In FIG. 18A, if it is judged that any one of operation buttons in thekey operating section 17 has been operated (YES in Step S201), or if itis judged that the portable phone has been picked up (YES in Step S202)during execution of the projection mode, the projection mode issuspended, and the display mode is switched to the direct viewing mode(Step S203). In this example, judgment as to whether the portable phonehas been picked up is made based on a detection signal from theacceleration sensor to be inputted from the sensor unit 210 to thecontroller 211 shown in FIGS. 2, 9, and 12. Specifically, if theacceleration speed is over a predetermined threshold value, it is judgedthat the portable phone has been picked up.

In FIG. 18B, judgment as to whether a phone call/electronic mail hasbeen received is made (Step S204) in addition to the judgment processshown in FIG. 18A. Adding the judgment step S204 prevents likelihoodthat a person might inadvertently pick up the portable phone or approachthe portable phone in response to a ring tone indicating receiving aphone call or an electronic mail, resulting in that laser light could beerroneously irradiated onto the person.

In FIG. 19A, the sub camera 15 attached to the same surface as the maindisplay section 14 is activated during execution of the projection mode(Step S211), and an image picked up by the sub camera 15 is subjected toimage processing by the image processing unit 204. The image processingunit 204 performs a face recognizing process based on the picked upimage (Step S212). If a face of a person is detected in the picked upimage (YES in Step S213), the image processing unit 204 transmits asignal indicating the detection to the controller 211. Then, thecontroller 211 suspends the projection mode and switches the displaymode to the direct viewing mode in response to receiving the facedetection signal from the image processing unit 204 (Step S214).

In this example, a face recognizing process is performed based on apicked up image from the sub camera 15, and judgment is made as towhether a face has approached the main display section 14.Alternatively, in place of or in addition to the above, a personrecognition may be made based on a picked up image from the sub camera15, and the display mode is switched to the direct viewing mode, basedon a judgment that a person has approached the main display section 14at a position closer than a threshold distance. Further alternatively, aface recognition and a person recognition may be performed, using animage picked up by the main camera 20 disposed on the rear surface ofthe portable phone, in addition to an image picked up by the sub camera15 to judge whether a face and a person has approached. In thearrangements of Examples 2 and 3, since the projection opening is formedin the top portion of the upper casing 11, projection may be performedin a state that the upper casing 11 is half-opened. In this case,photographing the exterior of the portable phone by the sub camera 15 isdifficult. Therefore, in the above usage state, a person and/or a faceis recognized based on an image picked up by the main camera 20.

In FIG. 19B, a folding angle of the portable phone is monitored, basedon a signal from the sensor unit 210 (the hinge sensor) during executionof the projection mode (Step S221). If it is judged that the foldingangle is improperly set (YES in Step S222), the controller 211 suspendsthe projection mode and switches the display mode to the direct viewingmode (Step S223).

As described above, there is likelihood that laser light may beerroneously irradiated onto a person e.g. when the laser lightirradiation direction is directed upwardly, in a state that the uppercasing 11 of the portable phone is opened with an undesirable angle. Inview of this, erroneous irradiation of laser light can be prevented bysuspending the projection mode in response to a detection that thefolding angle of the portable phone is improperly set during executionof the projection mode, as shown in the control process in FIG. 19B.

FIGS. 20A, 20B, and 20C are process flows to be executed at the time ofactivating the portable phone.

FIG. 20A corresponds to the arrangements in Examples 1 and 2. When theelectric power source of the portable phone is turned on (Step S231), itis judged whether the PDLCs 105 and 133 are in an off-state (Step S232).If it is judged that the PDLCs 105 and 133 are not in an off-state (NOin Step S232), the PDLCs 105 and 133 are turned off (Step S233).Thereafter, the portable phone is activated.

FIG. 20B corresponds to the arrangement in Example 3. When the electricpower source of the portable phone is turned on (Step S231), it isjudged whether the polarized light rotator 140 is in an off-state (StepS234). If it is judged that the polarized light rotator 140 is not in anoff-state (NO in Step S234), the polarized light rotator 140 is turnedoff (Step S235). Thereafter, the portable phone is activated.

According to the processes shown in FIGS. 20A and 20B, at the time ofactivating the portable phone, the PDLCs 105 and 130 are always set toan off-state. Further, since the polarized light rotator 140 is set toan off-state, there is no likelihood that laser light having a highcoherence might be erroneously emitted to the exterior of the portablephone, after the portable phone is activated.

FIG. 20C corresponds to the arrangements in Examples 2 and 3. When theelectric power source of the portable phone is turned on (Step S231), itis judged whether the liquid crystal panel 134 to be used in rendering adiffraction pattern is in a black image display state (Step S236). If itis judged that the liquid crystal panel 134 is not in a black imagedisplay state (NO in Step S236), the liquid crystal panel 134 is set toa black image display state (Step S237). Thereafter, the portable phoneis activated.

According to the process shown in FIG. 20C, at the time of activatingthe portable phone, the liquid crystal panel 134 is always set to ablack image display state. In the case laser light should be transmittedthrough the PDLC 133 or the polarized beam splitter 141, the laser lightis blocked by the liquid crystal panel 134. Thus, this arrangementenables to prevent likelihood that laser light having a high coherencemight be erroneously emitted to the exterior of the portable phone,after the portable phone is activated.

Next, an inherent process to be performed at the time of setting theprojection mode is described.

FIGS. 21A and 21B are diagrams relating to display of a battery residualamount and a radio receiving state.

Referring to FIG. 21A, when the projection mode is set, display of abattery residual amount and a radio receiving state is turned off (StepS311). During execution of the projection mode, the controller 211monitors the battery residual amount based on battery information to besupplied from the electric power source unit 209 (Step S312). If it isjudged that the monitored battery residual amount is under a thresholdvalue B0 (YES in Step S313), the controller 211 causes the imageprocessing unit 204 to perform a process of superimposedly displayingthe battery information on a projection screen (Step S314).

In this example, the battery information is displayed by e.g. a methodfor displaying characters indicating that the battery residual amount isdecreasing on a screen, or a method for displaying the battery residualamount in terms of a scale. Alternatively, the display may beintermittently performed at a predetermined cycle, or the display may bechanged in a stepwise manner, as the battery residual amount isdecreased.

In FIG. 21A, the battery information is notified by display.Alternatively, the battery information may be notified by audio sounds.Further alternatively, as shown in FIG. 21B, if it is judged that thebattery residual amount is under the threshold value B0 (YES in StepS313), the brightness of a display image may be gradually reduced inaccordance with the battery residual amount (Step S315). In themodification, the controller 211 supplies a signal for changing thebrightness of a display image to the laser driver 201.

FIGS. 22A and 22B are control process flows relating to a projectedimage. The process flows correspond to the arrangement in Example 1.

Referring to FIG. 21A, a manner for placing a portable phone withrespect to a desk surface or the like is detected (Step S401). Ahologram orientation is determined depending on the placement manner(Step S402).

In the case where an image is projected, there are supposed, as a mannerfor placing a portable phone with respect to a desk surface or the like,a manner that the rear surface of the lower casing 12 is in planecontact with a placement plane in a state that the portable phone isfolded with a predetermined angle (vertical placement manner); and amanner that the side surfaces of the upper casing 11 and the lowercasing 12 are in plane contact with a placement plane in a state thatthe portable phone is folded with a predetermined angle (horizontalplacement manner). A vertical orientation/horizontal orientation of theliquid crystal panel 106 with respect to a horizontal direction differsbetween the vertical placement manner and the horizontal placementmanner. In view of this, it is necessary to change a renderingorientation between the vertical placement manner and the horizontalplacement manner, in rendering a holographic image pattern on the liquidcrystal panel 106.

Referring to FIG. 21A, it is judged whether the portable phone isvertically or horizontally placed with respect to a placement plane(Step S401). The judgment is made based on a detection signal from thetilt sensor, out of the signals to be outputted from the sensor unit 210shown in FIG. 2. An orientation in which a holographic image pattern isrendered on the liquid crystal panel 106 is determined depending on ajudgment result (vertical placement manner or horizontal placementmanner) in Step S401 (Step S402). Then, a holographic image pattern isrendered on the liquid crystal panel 106 depending on the determinedrendering orientation, and an image is projected onto the projectionplane.

There are supposed, as the horizontal placement manner, a manner thatthe right side surface of the portable phone is in plane contact with aplacement plane (first horizontal placement manner), and a manner thatthe left side surface of the portable phone is in plane contact with aplacement plane (second horizontal placement manner). In view of this,it is necessary to judge whether the placement manner is the firsthorizontal placement manner or the second horizontal placement manner inStep S401, if it is judged that the placement manner is the horizontalplacement manner; and to determine the orientation in which aholographic image pattern is rendered on the liquid crystal panel 106,based on a judgment result as to whether the horizontal placement manneris the first horizontal placement manner or the second horizontalplacement manner in Step S402.

Further, it is convenient if the orientation of a display screen ischangeable, as necessary. For instance, a touch sensor may be providedon the portable phone, and the orientation of a display screen may bechanged by allowing the user to operate the portable phone through thetouch sensor, after the projection mode is started.

FIG. 22B is a process flow for correcting a trapezoidal distortion in aprojected image.

For instance, in the case where an image is projected onto a desksurface by placing the portable phone on the desk surface or the like ina vertical placement manner, a trapezoidal distortion in a projectedimage is changed depending on a change in the folding angle of the uppercasing 11. In view of this, it is necessary to change a process ofcorrecting a trapezoidal distortion depending on the folding angle ofthe upper casing 11 in the projection mode.

Referring to FIG. 22B, the folding angle of the portable phone isdetected (Step S411). The detection is performed based on a signal fromthe hinge sensor, out of the signals to be outputted from the sensorunit 210 shown in FIG. 2. A process of correcting a trapezoidaldistortion is determined, depending on a detection result in Step S411(Step S412). Then, signal generation is performed by the imageprocessing unit 204 in accordance with the determined correctingprocess, and a holographic image pattern whose trapezoidal distortionhas been corrected is rendered on the liquid crystal panel 106.

FIG. 23 is a diagram showing a usage state, in the case where theportable phone as one of the examples is used in a TV conference system.For sake of convenience, FIG. 23 shows a usage state in which theportable phone having the arrangement of Example 1 is used. In the casewhere the portable phone having the arrangement of Example 2, 3 is used,the upper casing 11 is folded to such a position that the projectionopening is directed toward a wall.

Referring to FIG. 23, the reference numeral 30 indicates a connectionplug for supplying an AC electric power source to the portable phone,and 31 indicates an electric power source line. The connection plug 30is connected to the plug connecting section 24 shown in FIG. 1. Theportable phone is set to the projection mode. The user is seated on therear side of the portable phone.

An image of the user or the like is picked up by the main camera 20,subjected to image processing by the image processing unit 204, and thentransmitted to a terminal device of a recipient through thecommunications processing unit 208. Image information received from therecipient terminal device is transmitted to the image processing unit204 through the communications processing unit 208, and rendered on theliquid crystal panel 106 as a holographic image pattern. Accordingly, animage of the recipient or the like image is projected on a wall surface.

The user's voice is collected by the microphone 18, and transmitted tothe recipient terminal device through the communications processing unit208. Audio information received from the recipient terminal device istransmitted to the microphone/speaker unit 207 through thecommunications processing unit 208, and outputted to the externalspeaker 21.

In this way, using the portable phone in the projection mode enables toconfigure a TV conference system. The embodiment is advantageous inremarkably enhancing the usability and use value of the portable phoneby adding a projection mode.

Some of the examples of the present invention have been described in theforegoing section. However, the present invention is not limited to theexamples. Further, the embodiment of the present invention may bechanged in various ways other than the above.

For instance, the present invention is applicable to a portable terminaldevice other than the portable phone, such as PDA (Personal DigitalAssistant). The present invention is also applicable to aninstallation-type display device.

In Example 1, an image is projected through the main display section 14.Alternatively, an image may be projected through the sub image section19. In the modification, a message that the projector is set to theprojection mode is displayed on the main display section 14 with in thedirect viewing mode.

Further alternatively, the laser light source 101 and the light sourceunit 131 may be used in common for various purposes of use.

For instance, laser light to be emitted from the laser light source 101or the light source unit 131 may be utilized as a light source forflashlight emission. In the modification, for instance, optical pathseparating means for guiding light from the laser light source 101 orthe light source unit 131 to an optical system for flashlight emissionduring a photographic operation by a camera is provided, and the laserlight source 101 or the light source unit 131 is activated for pulselight emission.

Further alternatively, laser light to be emitted from the laser lightsource 101 or the light source unit 131 may be used in common for adistance sensor. In the modification, for instance, optical pathseparating means for guiding light from the laser light source 101 orthe light source unit 131 to an optical system for a distance sensorduring a distance measuring operation is provided. Either one of thelaser light source 101 and the light source unit 131 is activated forpulse light emission. Then, a distance to a targeted object iscalculated, based on a time difference between a timing of pulse lightemission and a timing of receiving reflection light from the targetedobject.

Further alternatively, laser light to be emitted from the laser lightsource 101 or the light source unit 131 may be used as flashlight havingvarious patterns.

The embodiment of the present invention may be changed or modified invarious ways as necessary, as far as such changes and modifications donot depart from the scope of the claims of the present inventionhereinafter defined.

1. An image display device, comprising: a light source; an opticalsystem which is operable to switch between a direct viewing mode ofmodulating light from the light source and displaying the modulatedlight on a display section, and a projection mode of modulating thelight from the light source and projecting the modulated light on aprojection plane; and a control circuit which controls the opticalsystem, wherein the control circuit sets the optical system to thedirect viewing mode at the time of activating an electric power sourceof the image display device.
 2. A portable terminal device, comprising:an image display device including: a light source; an optical systemwhich is operable to switch between a direct viewing mode of modulatinglight from the light source and displaying the modulated light on adisplay section, and a projection mode of modulating the light from thelight source and projecting the modulated light on a projection plane;and a control circuit which controls the optical system, wherein thecontrol circuit sets the optical system to the direct viewing mode atthe time of activating an electric power source of the portable terminaldevice.
 3. The portable terminal device according to claim 2, whereinthe control circuit sets the optical system to the projection mode, whenat least one operation input, other than an operation input for settingthe optical system to the projection mode, is performed.
 4. The portableterminal device according to claim 2, further comprising: a placementsensor which detects whether the portable terminal device is in aplacement state, wherein the control circuit sets the optical system tothe projection mode at least when the placement sensor detects that theportable terminal device is in the placement state.
 5. The portableterminal device according to claim 2, further comprising: a tiltchanging mechanism which changes a tilt angle of the display plane whichemits the light from the light source to an exterior of the portableterminal device; and a tilt sensor which detects the tilt angle of thedisplay plane, wherein the control circuit sets the optical system tothe projection mode at least when the tilt sensor detects that the tiltangle of the display plane is set to a predetermined angle.
 6. Theportable terminal device according to claim 2, wherein the controlcircuit sets the optical system to the projection mode at least when theportable terminal device is connected to a commercial electric powersource.
 7. The portable terminal device according to claim 2, furthercomprising: an error notification circuit which notifies an exterior ofthe portable terminal device of a notice that the portable terminaldevice is not allowed to set the optical system to the projection modeand/or of a procedure necessary for setting the optical system to theprojection mode, in the case where the portable terminal device is notallowed to set the optical system to the projection mode.
 8. Theportable terminal device according to claim 2, further comprising: asetting notification circuit which notifies an exterior of the portableterminal device of a notice that the optical system is set to theprojection mode in setting the optical system to the projection mode. 9.The portable terminal device according to claim 2, further comprising: ajudging circuit which judges whether the optical system is to be kept inthe projection mode, wherein the control circuit switches the opticalsystem to the direct viewing mode in response to a judgment by thejudging circuit that the optical system is not to be kept in theprojection mode.
 10. The portable terminal device according to claim 9,wherein the judging circuit judges that the optical system is not to bekept in the projection mode in response to manipulation of an operationinput section.
 11. The portable terminal device according to claim 9,wherein the judging circuit has a placement sensor which detects whetherthe portable terminal device is in a placement state, and judges thatthe optical system is not to be kept in the projection mode, when theplacement sensor detects that the portable terminal device is not in theplacement state.
 12. The portable terminal device according to claim 9,wherein the judging circuit judges that the optical system is not to bekept in the projection mode when a communication is received from anexternal terminal.
 13. The portable terminal device according to claim9, further comprising: a camera, wherein the judging circuit includes adetecting section which detects a human based on an image picked up bythe camera, and judges that the optical system is not to be kept in theprojection mode, when the human is detected by the detecting section.14. The portable terminal device according to claim 9, furthercomprising: a camera, wherein the judging circuit judges that theoptical system is not to be kept in the projection mode, when the camerais manipulated for use.